It is meant to engender feelings of peace and well-being but yoga has become a battleground as India tries to stop its ancient heritage being exploited by the West.

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The Indian government is furious that yoga practices dating back thousands of years are being "stolen" by gurus and fitness instructors in Europe and the United States.

Foreign practitioners are already said to have claimed hundreds of patents and copyrights on poses and techniques lifted straight from classical Indian yoga treatises.

"Yoga piracy is becoming very common and we are moving to do something about it," says Vinod Gupta, the head of a recently established Indian government taskforce on traditional knowledge and intellectual property theft.

"We know of at least 150 asanas [yoga positions] that have been pirated in the US, the UK, Germany and Japan. These were developed in India long ago and no one can claim them as their own."

In an effort to protect India's heritage, the taskforce has begun documenting 1,500 yoga postures drawn from classical yoga texts - including the writings of the Indian sage Patanjali, the first man to codify the art of yoga. The data is being stored in a digital library whose computerised contents will soon be made available to patents offices worldwide.

The worst 'culprits' are Indians based in America, where yoga has become a $30 billion (£16 billion) - a-year business - a growth fuelled by celebrity adherents such as Madonna.

Among Western gurus who have prompted the concern, according to an Indian official, is Bikram Choudhury, whose "Bikram" or "Vikram" method is currently one of the most fashionable styles in the West. A session involves a series of 26 poses in a room heated to 32C (90F) to 38C (100F), enabling pupils to adopt more "extreme" positions than at normal temperatures.

A spokesman for Mr Choudhury refused to discuss the taskforce report, but the guru has previously said that rather than claiming intellectual ownership of the individual postures themselves, he has copyrighted a sequence of poses, the dialogue that accompanies them and the environment in which they are performed during his classes. These, he claims, are all of his own devising.

The US Patents Office has issued 134 patents on yoga accessories, 150 yoga-related copyrights and 2,315 yoga trademarks, says the Indian taskforce. It also claims that Britain has approved at least 10 trademarks relating to yoga training aids that are mentioned in ancient texts.

According to one report, attempts have even been made in America to patent the syllable "om", the sacred sound with which Hindus begin their chants.

"No one should be able to claim ownership of these traditional postures," said Dr Gupta. "The information has been in the public domain in India for thousands of years. But, until now, it has only been available in languages which people in the outside world cannot understand."

Special computer software has been developed to translate the ancient texts into English, French, German, Spanish and Japanese.

"This is a very good idea," says B K S Iyengar, the 86-year old yoga guru credited with having introduced yoga to the West in the 1970s. "Yoga is an essential part of our heritage and India has to protect it."

The move is part of a larger project to document all sources of traditional Indian knowledge. The database contains details of thousands of herbal treatments drawn from age-old health systems. So far, 10 million of an estimated 30 million pages of texts in Sanskrit, Arabic and Persian have been translated and entered into the digital library.

India was alerted to commercial exploitation of its national heritage in 1995, when a US company was granted a patent on the wound-healing properties of turmeric.

Two years later, another company was granted a patent on basmati rice. India successfully challenged both patents.